From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751610AbeELNpc (ORCPT ); Sat, 12 May 2018 09:45:32 -0400 Received: from mail-io0-f181.google.com ([209.85.223.181]:39096 "EHLO mail-io0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750854AbeELNpa (ORCPT ); Sat, 12 May 2018 09:45:30 -0400 X-Google-Smtp-Source: AB8JxZr6UUFf+BwFeUyphi1J7rkOOl3zI6oFjnasacdCXURf+kFRhgMaZXfYfjd6gnHOOMBUcK/DwRvTutcM4HLR0yY= MIME-Version: 1.0 In-Reply-To: References: From: Kyungtae Kim Date: Sat, 12 May 2018 09:45:28 -0400 Message-ID: Subject: Fwd: KASAN: use-after-free Write in vgacon_scroll To: linux-kernel@vger.kernel.org, linux-fbdev@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ---------- Forwarded message ---------- From: Kyungtae Kim Date: Sat, May 12, 2018 at 9:44 AM Subject: KASAN: use-after-free Write in vgacon_scroll To: b.zolnierkie@samsung.com, dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Byoungyoung Lee , DaeRyong Jeong We report the crash: "KASAN: use-after-free Write in vgacon_scroll" This crash was found in v4.17-rc3. Specifically, memory access (write operation) is invalid, and it is detected by KASAN. C repro code: https://kiwi.cs.purdue.edu/static/alexkkid-fuzzer/repro-bd11a.c kernel config: https://kiwi.cs.purdue.edu/static/alexkkid-fuzzer/kernel-config-v4.17-rc3 Crash log: ============================================================== BUG: KASAN: use-after-free in memcpy include/linux/string.h:345 [inline] BUG: KASAN: use-after-free in scr_memcpyw include/linux/vt_buffer.h:49 [inline] BUG: KASAN: use-after-free in vgacon_scrollback_update drivers/video/console/vgacon.c:249 [inline] BUG: KASAN: use-after-free in vgacon_scroll+0x684/0x890 drivers/video/console/vgacon.c:1374 Write of size 3758 at addr ffff88011a8bf98e by task syz-executor1/3226 CPU: 0 PID: 3226 Comm: syz-executor1 Not tainted 4.17.0-rc3 #2 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0xc7/0x138 lib/dump_stack.c:113 print_address_description+0x6a/0x280 mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report+0x22f/0x350 mm/kasan/report.c:412 check_memory_region_inline mm/kasan/kasan.c:260 [inline] check_memory_region+0x13b/0x1a0 mm/kasan/kasan.c:267 memcpy+0x37/0x50 mm/kasan/kasan.c:303 memcpy include/linux/string.h:345 [inline] scr_memcpyw include/linux/vt_buffer.h:49 [inline] vgacon_scrollback_update drivers/video/console/vgacon.c:249 [inline] vgacon_scroll+0x684/0x890 drivers/video/console/vgacon.c:1374 con_scroll+0x2cc/0x330 drivers/tty/vt/vt.c:329 lf+0x247/0x290 drivers/tty/vt/vt.c:1122 do_con_trol+0x14f/0x5310 drivers/tty/vt/vt.c:1785 do_con_write.part.20+0x597/0x1b70 drivers/tty/vt/vt.c:2433 do_con_write drivers/tty/vt/vt.c:2790 [inline] con_write+0xb2/0xc0 drivers/tty/vt/vt.c:2786 n_tty_write+0x763/0xea0 drivers/tty/n_tty.c:2331 do_tty_write drivers/tty/tty_io.c:958 [inline] tty_write+0x48c/0x870 drivers/tty/tty_io.c:1042 redirected_tty_write+0xaf/0xc0 drivers/tty/tty_io.c:1063 __vfs_write+0x10d/0x610 fs/read_write.c:485 vfs_write+0x187/0x500 fs/read_write.c:549 ksys_write+0xd4/0x1a0 fs/read_write.c:598 __do_sys_write fs/read_write.c:610 [inline] __se_sys_write fs/read_write.c:607 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:607 do_syscall_64+0xa4/0x460 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x4497b9 RSP: 002b:00007fc0af9acc68 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fc0af9ad6cc RCX: 00000000004497b9 RDX: 0000000000001000 RSI: 0000000020000080 RDI: 0000000000000013 RBP: 000000000071bf58 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 0000000000009ee8 R14: 00000000006f0f88 R15: 00007fc0af9ad700 The buggy address belongs to the page: page:ffffea00046a2c00 count:1 mapcount:0 mapping:0000000000000000 index:0x0 compound_mapcount: 0 flags: 0x200000000008000(head) raw: 0200000000008000 0000000000000000 0000000000000000 00000001ffffffff raw: dead000000000100 dead000000000200 0000000000000000 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88011a8bff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff88011a8bff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff88011a8c0000: fb fb fb fc fc fb fb fb fc fc 00 00 00 fc fc fc ^ ffff88011a8c0080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff88011a8c0100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ============================================================== Thanks, Kyungtae Kim